Method for correcting water level of steam drum based on temperature and pressure

Abstract

This invention relates to a correctional method of water level in the steam drum based on the temperature and pressure that belongs to the heat process control field including the following steps: the temperature difference DeltaT is linear to the water supply flow increment in small range, DeltaQ=-kDeltaT, theDeltaQ is used as the feedforward value in the main circuit of the cascade control of the water level in the steam drum, to eliminate the adverse effect of 'false water level' on the water supply control. When the load increases,DeltaQ>0, and the steam drum working condition is nearly stable, the correctional value is 0; when the load decreases, the controlled water supply is suppressed, DeltaQ<0; when the water flow increases, the temperature T of the steam drum decreases and the water supply flow increment DeltaQ<0; when the water supply flow is nearly constant, the correctional value is 0; when the water supply flow decreases, the controlled supply flow increases, DeltaQ>0. This method introduces the effect of steam drum pressure and water temperature on the steam bubble in the steam drum water to correct the water level control, which suppresses the overshoot phenomenon and ensures the steady operation of the boiler.

Description

technical field [0001] The invention belongs to the field of thermal control, in particular to a method for correcting the water level of a steam drum based on temperature and pressure. Background technique [0002] The steam drum is a device for separating water and vapor in the boiler, and there is a large amount of steam-water mixture inside the steam drum. For the boiler steam drum, when the load increases, the steam flow rate increases, resulting in a decrease in the water vapor pressure in the steam drum, a corresponding decrease in the boiling point of the water, aggravated boiling, and an increase in the volume of the bubbles under the water surface, resulting in a sudden increase in the water level; On the one hand, when the feedwater flow rate increases, the feedwater with a lower temperature absorbs part of the heat from the original saturated steam-water mixture, which reduces the volume of the bubbles under the water surface, resulting in a drop in the water lev...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved in the present invention is to aim at the "false water level" phenomenon in boiler water level control, which will bring adverse effects on the steam drum liquid level control. For this shortcoming, it is necessary to correct the water level control of the steam drum.

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